1. Technical Field
The present invention relates to an electroluminescence apparatus, a method for manufacturing an electroluminescence apparatus, and an electronic apparatus.
2. Related Art
Recently, as a display device used for a display unit of various electronic apparatuses such as mobile phones, the practical application of an electroluminescence (EL) apparatus has been advancing. The EL apparatus is provided with a plurality of EL elements arranged regularly in a display area. The EL apparatus forms an image by causing the EL elements to emit light. The EL element is made up of a pair of electrodes and a light-emitting function layer that is sandwiched between the pair of electrodes. One of the pair of electrodes is a anode (i.e., pixel electrode), which is formed over an element substrate on which driving elements are formed. The other of the pair of electrodes is a negative electrode (i.e., common electrode), which is formed opposite the pixel electrodes. The light-emitting function layer includes at least an EL layer (EL material layer). These days, the use of an organic EL apparatus is increasing. The organic EL apparatus uses an organic EL material as its EL material. In addition, the use of a top-emission type organic EL apparatus is increasing. The top-emission type organic EL apparatus emits light from a negative-electrode side in order to improve luminance with effective use of emission light (luminescence).
One problem of a top-emission type organic EL apparatus is the resistance of a negative electrode (common electrode). The negative electrode is usually formed throughout an entire display area. In order to achieve both translucency and conductivity, the negative electrode is formed as a very thin metal layer that has a thickness of several nanometers (nm) to more than ten nanometers. Or, the negative electrode is made of a high resistance material such as ITO (indium oxide tin alloy) whose resistance is higher than that of metal. Accordingly, the negative electrode has a high surface resistance (sheet resistance). Therefore, the amount of supply of an electric current to organic EL elements decreases because of a voltage drop at and near the center of a display area. For this reason, display quality might deteriorate. In an effort to provide a solution to such a problem, the following method is disclosed in, for example, JP-A-2007-265756. A plurality of auxiliary lines (i.e., electric wiring) is formed on a counter-substrate-side surface of a partition wall. The counter-substrate-side surface is a surface that faces toward and is closer to a counter substrate. The partition wall separates a plurality of organic EL elements from one another. Each of the plurality of auxiliary lines is electrically connected to a negative electrode. The plurality of auxiliary lines extends in parallel with one another. The plurality of auxiliary lines is formed by means of a mask film deposition method. A mask that has gap opening is placed on a substrate to cover a surface of the substrate. Particles of a conductive material are discharged straight toward the substrate covered by the mask. The conductive material particles deposit at the gap opening of the mask. In this way, the auxiliary lines are formed. The layer thickness requirement of the auxiliary lines is less strict. That is, the requirement in terms of the dimension of the auxiliary wiring in the direction of a line normal to an element substrate is less severe. Therefore, it is possible to reduce the surface resistance described above, thereby alleviating the degradation of display quality.
However, the negative electrode with the auxiliary lines having the above features has a disadvantage in that the effect of actually reducing the surface resistance is not so great because the flowing direction of a cathode current is substantially limited to the extending direction described above. The reduction effect is increased if the auxiliary lines are formed in a grid pattern so that the auxiliary lines extend in two directions that are substantially perpendicular to each other, for example, the vertical direction and the horizontal direction. However, if the auxiliary lines are formed in such a grid pattern, a problem arises in that production cost increases because it is necessary to perform a mask film deposition step at least twice. In addition, if the auxiliary lines are formed in such a two-directional pattern, the coverage of a passivation film, which is formed on a counter-substrate-side surface of the cathode, deteriorates at an intersection, that is, at a point/region where the auxiliary lines intersect with each other. Because of the poorer coverage of the passivation film thereat, a problem arises in that reliability might decrease.